4 Replies Latest reply on Jan 24, 2013 2:32 PM by Sean Mullane

    Incremental Refresh does not alter historical records

    Mike Penney

      I noticed that while new records were appearing in the incremental extract, changes or deletions to existing records were not being reflected in my reports. I then found the following article while waiting for my next scheduled update.

       

      Tableau be careful using an Incremental Refresh

       

      April 20th, 2012 

       

      Perhaps the title of this post is a little extreme but I have spent some time
      trying to speed up the refreshing of my Tableau extracts recently and began to
      use incremental extract refreshes where I thought it was appropriate – for
      example with order data just adding yesterdays orders each day.

       

      On closer inspection I noticed that with the data warehouse I’m using the way
      it’s designed is to run updates on existing records rather than inserting a new
      record to reflect a change in the underlying data. I was reading an article on
      the Tableau site about Optimising Incremental Refreshes and noticed a warning towards
      the end of the article saying “Updates to existing data and deletions
      are only included in full refreshes

       

      In other words if you’re using a data source where the data can alter
      historically and your Tableau report needs to match these changes to the
      underlying data then a Full Refresh must be used. The incremental refresh would
      miss the alterations and only insert new records.

       

      Make sure the data source is checked to be sure that none of the data can
      change historically OR if it can change historically check these changes don’t
      have to be reflected in the reporting.

       

      Note Tableau allows an extract to be refreshed both Incrementally and Fully
      so dependent on the requirements it could be possible to run daily incremental
      updates during the week and carry out full extracts on the weekend to capture
      historic changes, for example.